1. Statement of the Technical Field
The inventive arrangements relate generally to the field of protecting film against illegal copying, and in particular, to an improved method for film encoding to facilitate the identification of the source of films illegally copied by camcorders and to media encoded in accordance with the method.
2. Description of the Related Art
Piracy issues in connection with the theatrical exhibition of motion picture films are well known. Once a film distributor distributes prints of a motion picture film to exhibitors for theatrical exhibition, a certain degree of control over the product is lost. In the regular course of exhibiting the film, a customer in the theater may surreptitiously record the film using, e.g., a hand held camcorder. At a more sophisticated level, a person seeking to obtain an illegal copy of a film print may gain access to a theater projection booth in collusion with an employee of the exhibitor and make a copy of the film after hours in a relatively controlled environment. In such an environment, the audio from the projection equipment can be directly fed to the camcorder. A tripod can be used to ensure a clear and steady picture. As a result, an illicit copy can be made. Alternatively, the print itself may be scanned to create a video master.
In 1982, the Motion Picture Association of America (MPAA), together with the Kodak Corporation, developed a technology for uniquely identifying film prints. This technology is commonly known as Coded Anti-piracy (CAP) coding. The code is a series of dots in the picture that are added as the print is manufactured. Approximately one out of every hundred frames contains four tiny dots that have been added to the image. Generally, 11 CAP-coded frames are required to reconstitute the serial number of the movie print. Each unique configuration of dots corresponds to a print number. The film prints are usually coded for each theatre in which a film is distributed.
Historically, aiming an analog camcorder at a theatre screen produced a poor quality, flickering image, but the coding dots usually survived the copying and reproduction process. Improved digital camcorders not only take better pictures, but the video compression algorithms that are commonly employed when the pirated film is stored in a digital format or transported over the internet, tend to obliterate the CAP codes. Because the CAP coding scheme is defeated if even only a small number of the coding dots are lost in image processing, the viability of CAP coding has diminished with the advent of digital video compression and distribution technologies.
Another limitation of the CAP coding system is that a total of 2023 unique configurations were developed in 1982. At the time, this was sufficient because it was roughly equivalent to the number of theaters in operation at the time and substantially exceeded the number of prints that had been made in connection with even the largest motion picture releases. Today there are over 20,000 theaters worldwide and major motion picture releases of more than 5,000 prints are increasingly common. Accordingly, there are an insufficient number of codes to uniquely identify each film print that is distributed.
Yet another limitation of the CAP coding system concerns the size of the code image superimposed on the print. The dots representing the code are extremely small and diffuse. These characteristics result in disintegration of the image during compression. Because the CAP code image configuration is the unique identifier, the entire image must survive. Therefore CAP coding is dependent upon 100% image survival.
Further, the frequency of code image repetition in CAP coding systems increases the likelihood that the public will see the image. This is undesirable as it can distract viewers from the film content or cause them to form an opinion that a particular theatre shows poor quality prints. Accordingly, there is a pressing need for a successor to CAP coding to detect film piracy.